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1 features ? fast read access time ? 70 ns automatic page write operation ? internal address and data latches for 64 bytes ? internal control timer fast write cycle times ? page write cycle time: 3 ms or 10 ms maximum ? 1 to 64-byte page write operation low power dissipation ? 80 ma active current ? 3 ma standby current hardware and software data protection data polling for end of write detection high reliability cmos technology ? endurance: 10 4 or 10 5 cycles ? data retention: 10 years single 5v 10% supply cmos and ttl compatible inputs and outputs jedec approved byte-wide pinout full military, commercial, and industrial temperature ranges description the AT28HC256 is a high-performance electrically erasable and programmable read only memory. its 256k of memory is organized as 32,768 words by 8 bits. manufac- tured with atmel ? s advanced nonvolatile cmos technology, the AT28HC256 offers 256 (32k x 8) high-speed parallel eeprom AT28HC256 rev. 0007i ? 12/99 pin configurations pin name function a0 - a14 addresses ce chip enable oe output enable we write enable i/o0 - i/o7 data inputs/outputs nc no connect dc don ? t connect tsop to p v i ew 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 oe a11 a9 a8 a13 we vcc a14 a12 a7 a6 a5 a4 a3 a10 ce i/o7 i/o6 i/o5 i/o4 i/o3 gnd i/o2 i/o1 i/o0 a0 a1 a2 lcc, plcc top view note: plcc package pins 1 and 17 are don ? t connect. 5 6 7 8 9 10 11 12 13 29 28 27 26 25 24 23 22 21 a6 a5 a4 a3 a2 a1 a0 nc i/o0 a8 a9 a11 nc oe a10 ce i/o7 i/o6 4 3 2 1 32 31 30 14 15 16 17 18 19 20 i/o1 i/o2 gnd dc i/o3 i/o4 i/o5 a7 a12 a14 dc vcc we a13 pga to p v i ew (continued) cerdip, pdip, flatpack to p v i ew 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 a14 a12 a7 a6 a5 a4 a3 a2 a1 a0 i/o0 i/o1 i/o2 gnd vcc we a13 a8 a9 a11 oe a10 ce i/o7 i/o6 i/o5 i/o4 i/o3
AT28HC256 2 access times to 70 ns with power dissipation of just 440 mw. when the AT28HC256 is deselected, the standby current is less than 5 ma. the AT28HC256 is accessed like a static ram for the read or write cycle without the need for external components. the device contains a 64-byte page register to allow writing of up to 64 bytes simultaneously. during a write cycle, the address and 1 to 64 bytes of data are internally latched, freeing the addresses and data bus for other operations. following the initiation of a write cycle, the device will auto- matically write the latched data using an internal control timer. the end of a write cycle can be detected by data polling of i/o 7 . once the end of a write cycle has been detected a new access for a read or write can begin. atmel ? s 28hc256 has additional features to ensure high quality and manufacturability. the device utilizes internal error correction for extended endurance and improved data retention characteristics. an optional software data protec- tion mechanism is available to guard against inadvertent writes. the device also includes an extra 64 bytes of eeprom for device identification or tracking. block diagram absolute maximum ratings* temperature under bias ................................ -55 c to +125 c *notice: stresses beyond those listed under ? absolute maximum ratings ? may cause permanent dam- age to the device. this is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability storage temperature ..................................... -65 c to +150 c all input voltages (including nc pins) with respect to ground ...................................-0.6v to +6.25v all output voltages with respect to ground .............................-0.6v to v cc + 0.6v voltage on oe and a9 with respect to ground ...................................-0.6v to +13.5v
AT28HC256 3 device operation read: the AT28HC256 is accessed like a static ram. when ce and oe are low and we is high, the data stored at the memory location determined by the address pins is asserted on the outputs. the outputs are put in the high impedance state when either ce or oe is high. this dual- line control gives designers flexibility in preventing bus con- tention in their system. byte write: a low pulse on the we or ce input with ce or we low (respectively) and oe high initiates a write cycle. the address is latched on the falling edge of ce or we , whichever occurs last. the data is latched by the first rising edge of ce or we . once a byte write has been started it will automatically time itself to completion. once a pro- gramming operation has been initiated and for the duration of t wc , a read operation will effectively be a polling operation. page write: the page write operation of the AT28HC256 allows 1 to 64 bytes of data to be written into the device during a single internal programming period. a page write operation is initiated in the same manner as a byte write; the first byte written can then be followed by 1 to 63 additional bytes. each successive byte must be written within 150 s (t blc ) of the previous byte. if the t blc limit is exceeded the at28c256 will cease accepting data and commence the internal programming operation. all bytes during a page write operation must reside on the same page as defined by the state of the a6 - a14 inputs. that is, for each we high to low transition during the page write operation, a6 - a14 must be the same. the a0 to a5 inputs are used to specify which bytes within the page are to be written. the bytes may be loaded in any order and may be altered within the same load period. only bytes which are specified for writing will be written; unnec- essary cycling of other bytes within the page does not occur. data polling: the AT28HC256 features data polling to indicate the end of a write cycle. during a byte or page write cycle an attempted read of the last byte written will result in the complement of the written data to be presented on i/o 7 . once the write cycle has been completed, true data is valid on all outputs, and the next write cycle may begin. data polling may begin at anytime during the write cycle. toggle bit: in addition to data polling the AT28HC256 provides another method for determining the end of a write cycle. during the write operation, successive attempts to read data from the device will result in i/o 6 toggling between one and zero. once the write has completed, i/o 6 will stop toggling and valid data will be read. testing the toggle bit may begin at any time during the write cycle. data protection: if precautions are not taken, inad- vertent writes to any 5-volt-only nonvolatile memory may occur during transition of the host system power supply. atmel has incorporated both hardware and software fea- tures that will protect the memory against inadvertent writes. hardware protection: hardware features protect against inadvertent writes to the AT28HC256 in the follow- ing ways: (a) v cc sense ? if v cc is below 3.8v (typical) the write function is inhibited; (b) v cc power-on delay ? once v cc has reached 3.8v the device will automatically time out 5 ms typical) before allowing a write; (c) write inhibit ? hold- ing any one of oe low, ce high or we high inhibits write cycles; and (d) noise filter ? pulses of less than 15 ns (typi- cal) on the we or ce inputs will not initiate a write cycle. software data protection: a software controlled data protection feature has been implemented on the AT28HC256. when enabled, the software data protection (sdp), will prevent inadvertent writes. the sdp feature may be enabled or disabled by the user; the AT28HC256 is shipped from atmel with sdp disabled. sdp is enabled by the host system issuing a series of three write commands; three specific bytes of data are written to three specific addresses (refer to ? software data protec- tion ? algorithm). after writing the 3-byte command sequence and after t wc the entire AT28HC256 will be pro- tected against inadvertent write operations. it should be noted, that once protected the host may still perform a byte or page write to the AT28HC256. this is done by preceding the data to be written by the same 3-byte command sequence. once set, sdp will remain active unless the disable com- mand sequence is issued. power transitions do not disable sdp and sdp will protect the AT28HC256 during power-up and power-down conditions. all command sequences must conform to the page write timing specifications. it should also be noted that the data in the enable and disable com- mand sequences is not written to the device and the mem- ory addresses used in the sequence may be written with data in either a byte or page write operation. after setting sdp, any attempt to write to the device without the three byte command sequence will start the internal write timers. no data will be written to the device; however, for the duration of t wc , read operations will effectively be polling operations. device identification: an extra 64 bytes of eeprom memory are available to the user for device identification. by raising a9 to 12v 0.5v and using address locations 7fc0h to 7fffh the additional bytes may be written to or read from in the same manner as the regular memory array. optional chip erase mode: the entire device can be erased using a 6-byte software code. please see ? soft- ware chip erase ? application note for details.
AT28HC256 4 notes: 1. x can be v il or v ih . 2. refer to ac programming waveforms. 3. v h = 12.0v 0.5v. dc and ac operating range AT28HC256-70 AT28HC256-90 AT28HC256-12 operating temperature (case) com. 0 c - 70 c0 c - 70 c0 c - 70 c ind. -40 c - 85 c-40 c - 85 c-40 c - 85 c mil. -55 c - 125 c-55 c - 125 c v cc power supply 5v 10% 5v 10% 5v 10% operating modes mode ce oe we i/o read v il v il v ih d out write (2) v il v ih v il d in standby/write inhibit v ih x (1) xhigh z write inhibit x x v ih write inhibit x v il x output disable x v ih xhigh z chip erase v il v h (3) v il high z dc characteristics symbol parameter condition min max units i li input load current v in = 0v to v cc + 1v 10 a i lo output leakage current v i/o = 0v to v cc 10 a i sb1 v cc standby current ttl ce = 2.0v to v cc AT28HC256-90, -12 3 ma AT28HC256-70 60 ma i sb2 v cc standby current cmos ce = v cc - 0.3v to v cc AT28HC256-90, -12 300 a i cc v cc active current f = 5 mhz; i out = 0 ma 80 ma v il input low voltage 0.8 v v ih input high voltage 2.0 v v ol output low voltage i ol = 6.0 ma 0.45 v v oh output high voltage i oh = -4 ma 2.4 v
AT28HC256 5 ac read waveforms (1)(2)(3)(4) notes: 1. ce may be delayed up to t acc - t ce after the address transition without impact on t acc . 2. oe may be delayed up to t ce - t oe after the falling edge of ce without impact on t ce or by t acc - t oe after an address change without impact on t acc . 3. t df is specified from oe or ce whichever occurs first (c l = 5 pf). 4. this parameter is characterized and is not 100% tested. input test waveforms and measurement level output test load note: 1. this parameter is characterized and is not 100% tested. ac read characteristics symbol parameter AT28HC256-70 at28c256-90 AT28HC256-12 units minmaxminmaxminmax t acc address to output delay 70 90 120 ns t ce (1) ce to output delay 70 90 120 ns t oe (2) oe to output delay 0 35 0 40 0 50 ns t df (3)(4) ce or oe to output float 035040050ns t oh output hold from oe , ce or address, whichever occurred first 000ns t r , t f < 5 ns pin capacitance f = 1 mhz, t = 25 c (1) symbol typ max units conditions c in 46pfv in = 0v c out 812pfv out = 0v
AT28HC256 6 note: 1. nr = no restriction. ac write waveforms we controlled ce controlled ac write characteristics symbol parameter min max units t as , t oes address, oe setup time 0 ns t ah address hold time 50 ns t cs chip select setup time 0 ns t ch chip select hold time 0 ns t wp write pulse width (we or ce )100ns t ds data setup time 50 ns t dh , t oeh data, oe hold time 0 ns t dv time to data valid nr (1)
AT28HC256 7 page mode write waveforms (1)(2) notes: 1. a6 through a14 must specify the same page address during each high to low transition of we (or ce ). 2. oe must be high only when we and ce are both low. chip erase waveforms page mode write characteristics symbol parameter min typ max units t wc write cycle time (option available) AT28HC256 5 10 ms AT28HC256f 2 3 ms t as address setup time 0 ns t ah address hold time 50 ns t ds data setup time 50 ns t dh data hold time 0 ns t wp write pulse width 100 ns t blc byte load cycle time 150 s t wph write pulse width high 50 ns t s = t h = 5 sec (min.) t w = 10 msec (min.) v h = 12.0v 0.5v
AT28HC256 8 software data protection enable algorithm (1) notes for software program code: 1. data format: i/o7 - i/o0 (hex); address format: a14 - a0 (hex). 2. write protect state will be activated at end of write even if no other data is loaded. 3. write protect state will be deactivated at end of write period even if no other data is loaded. 4. 1 to 64 bytes of data are loaded. software data protection disable algorithm (1) software protected write cycle waveforms (1)(2) notes: 1. a6 through a14 must specify the same page address during each high to low transition of we (or ce ) after the software code has been entered. 2. oe must be high only when we and ce are both low. load data aa to address 5555 load data 55 to address 2aaa load data a0 to address 5555 load data xx to any address (4) load last byte to last address enter data protect state writes enabled (2) load data aa to address 5555 load data 55 to address 2aaa load data 80 to address 5555 load data aa to address 5555 load data 20 to address 5555 load data xx to any address (4) load last byte to last address load data 55 to address 2aaa exit data protect state (3)
AT28HC256 9 notes: 1. these parameters are characterized and not 100% tested. 2. see ? ac read characteristics ? on page 5. data polling waveforms notes: 1. these parameters are characterized and not 100% tested. 2. see ? ac read characteristics ? on page 5. toggle bit waveforms notes: 1. toggling either oe or ce or both oe and ce will operate toggle bit. 2. beginning and ending state of i/o6 will vary. 3. any address location may be used but the address should not vary. data polling characteristics (1) symbol parameter min typ max units t dh data hold time 0 ns t oeh oe hold time 0 ns t oe oe to output delay (2) ns t wr write recovery time 0 ns toggle bit characteristics (1) symbol parameter min typ max units t dh data hold time 10 ns t oeh oe hold time 10 ns t oe oe to output delay (2) ns t oehp oe high pulse 150 ns t wr write recovery time 0 ns
AT28HC256 10
AT28HC256 11 ordering information (1) t acc (ns) i cc (ma) ordering code package operation range active standby 70 80 60 AT28HC256(e,f)-70jc AT28HC256(e,f)-70pc 32j 28p6 commercial (0 c to 70 c) 0.3 AT28HC256(e,f)-70ji AT28HC256(e,f)-70pi 32j 28p6 industrial (-40 c to 85 c) 90 80 0.3 AT28HC256(e,f)-90jc AT28HC256(e,f)-90pc 32j 28p6 commercial (0 c to 70 c) AT28HC256(e,f)-90ji AT28HC256(e,f)-90pi 32j 28p6 industrial (-40 c to 85 c) 80 0.3 AT28HC256(e,f)-90dm/883 AT28HC256(e,f)-90fm/883 AT28HC256(e,f)-90lm/883 AT28HC256(e,f)-90um/883 28d6 28f 32l 28u military/883c class b, fully compliant (-55 c to 125 c) 120 80 0.3 AT28HC256(e,f)-12jc AT28HC256(e,f)-12pc AT28HC256(e,f)-12sc AT28HC256(e,f)-12tc 32j 28p6 28s 28t commercial (0 c to 70 c) 80 0.3 AT28HC256(e,f)-12ji AT28HC256(e,f)-12pi AT28HC256(e,f)-12si AT28HC256(e,f)-12ti 32j 28p6 28s 28t industrial (-40 c to 85 c) 80 0.3 AT28HC256(e,f)-12dm/883 AT28HC256(e,f)-12fm/883 AT28HC256(e,f)-12lm/883 AT28HC256(e,f)-12um/883 28d6 28f 32l 28u military/883c class b, fully compliant (-55 c to 125 c) package type 28d6 28-lead, 0.600" wide, non-windowed, ceramic dual inline package (cerdip) 28f 28-lead, non-windowed, ceramic bottom-brazed flat package (flatpack) 32j 32-lead, plastic j-leaded chip carrier (plcc) 32l 32-pad, non-windowed, ceramic leadless chip carrier (lcc) 28p6 28-lead, 0.600" wide, plastic dual inline package (pdip) 28s 28-lead, 0.300" wide plastic gull wing small outline (soic) 28t 28-lead, plastic thin small outline package (tsop) 28u 28-pin, ceramic pin grid array (pga) w die options blank standard device: endurance = 10k write cycles; write time = 10 ms e high endurance option: endurance = 100k write cycles f fast write option: write time = 3 ms
AT28HC256 12 note: 1. see ? valid part numbers ? table on next page. 90 80 0.3 5962-88634 03 ux 5962-88634 03 xx 5962-88634 03 yx 5962-88634 03 zx 28u 28d6 32l 28f military/883c class b, fully compliant (-55 c to 125 c) 80 0.3 5962-88634 04 ux 5962-88634 04 xx 5962-88634 04 yx 5962-88634 04 zx 28u 28d6 32l 28f military/883c class b, fully compliant (-55 c to 125 c) 120 80 0.3 5962-88634 01 ux 5962-88634 01 xx 5962-88634 01 yx 5962-88634 01 zx 28u 28d6 32l 28f military/883c class b, fully compliant (-55 c to 125 c) 80 0.3 5962-88634 02 ux 5962-88634 02 xx 5962-88634 02 yx 5962-88634 02 zx 28u 28d6 32l 28f military/883c class b, fully compliant (-55 c to 125 c) ordering information (1) (continued) t acc (ns) i cc (ma) ordering code package operation range active standby package type 28d6 28-lead, 0.600" wide, non-windowed, ceramic dual inline package (cerdip) 28f 28-lead, non-windowed, ceramic bottom-brazed flat package (flatpack) 32j 32-lead, plastic j-leaded chip carrier (plcc) 32l 32-pad, non-windowed, ceramic leadless chip carrier (lcc) 28p6 28-lead, 0.600" wide, plastic dual inline package (pdip) 28s 28-lead, 0.300" wide plastic gull wing small outline (soic) 28t 28-lead, plastic thin small outline package (tsop) 28u 28-pin, ceramic pin grid array (pga) w die options blank standard device: endurance = 10k write cycles; write time = 10 ms e high endurance option: endurance = 100k write cycles f fast write option: write time = 3 ms
AT28HC256 13 ordering information note previous data sheets included the low power suffixes l, le and lf on the AT28HC256 for 120 ns and 90 ns speeds. the low power parameters are now standard; therefore, the l, le and lf suffixes are no longer required. valid part numbers the following table lists standard atmel products that can be ordered: device numbers speed package and temperature combinations AT28HC256 70 jc, ji, pc, pi AT28HC256 90 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 AT28HC256e 90 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 AT28HC256f 90 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 AT28HC256 12 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 AT28HC256e 12 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 AT28HC256f 12 jc, ji, pc, pi, tc, ti, dm/883, fm/883, um/883 die products reference section: parallel eeprom die products
AT28HC256 14 packaging information 1.49(37.9) 1.44(36.6) pin 1 .610(15.5) .510(13.0) .098(2.49) max .005(.127) min .060(1.52) .015(.381) .023(.584) .014(.356) .065(1.65) .045(1.14) 0 15 ref .700(17.8) max .620(15.7) .590(15.0) .015(.381) .008(.203) .110(2.79) .090(2.29) .200(5.08) .125(3.18) seating plane .225(5.72) max 1.300(33.02) ref pin #1 id .370(9.40) .250(6.35) .019(.483) .015(.381) .050(1.27) bsc .045(1.14) max .119(3.02) .087(2.21) .045(1.14) .026(.660) .286(7.26) .274(6.96) .077(1.96) .043(1.09) .006(.152) .004(.102) .416(10.6) .384(9.75) .728(18.5) .712(18.1) .045(1.14) x 45? pin no. 1 identify .025(.635) x 30? - 45? .012(.305) .008(.203) .021(.533) .013(.330) .530(13.5) .490(12.4) .030(.762) .015(.381) .095(2.41) .060(1.52) .140(3.56) .120(3.05) .032(.813) .026(.660) .050(1.27) typ .553(14.0) .547(13.9) .595(15.1) .585(14.9) .300(7.62) ref .430(10.9) .390(9.90) at contact points .022(.559) x 45? max (3x) .453(11.5) .447(11.4) .495(12.6) .485(12.3) *controlling dimension: millimeters 28d6 , 28-lead, 0.600" wide, non-windowed, ceramic dual inline package (cerdip) dimensions in inches and (millimeters) mil-std-1835 d-10 config a 28f , 28-lead, non-windowed, ceramic bottom- brazed flat package (flatpack) dimensions in inches and (millimeters) mil-std-1835 f-12 config b 32j , 32-lead, plastic j-leaded chip carrier (plcc) dimensions in inches and (millimeters) jedec standard ms-016 ae 32l , 32-pad, non-windowed, ceramic leadless chip carrier (lcc) dimensions in inches and (millimeters)* mil-std-1835 c-12
AT28HC256 15 packaging information 1.47(37.3) 1.44(36.6) pin 1 .566(14.4) .530(13.5) .090(2.29) max .005(.127) min .065(1.65) .015(.381) .022(.559) .014(.356) .065(1.65) .041(1.04) 0 15 ref .630(16.0) .590(15.0) .690(17.5) .610(15.5) .012(.305) .008(.203) .110(2.79) .090(2.29) .161(4.09) .125(3.18) seating plane .220(5.59) max 1.300(33.02) ref *controlling dimension: millimeters index mark area 0.55 (0.022) bsc 0.20 (0.008) 0.10 (0.004) 7.15 (0.281) ref 8.10 (0.319) 7.90 (0.311) 1.25 (0.049) 1.05 (0.041) 0.27 (0.011) 0.18 (0.007) 11.9 (0.469) 11.7 (0.461) 13.7 (0.539) 13.1 (0.516) 0 5 0.20 (0.008) 0.15 (0.006) ref 0.70 (0.028) 0.30 (0.012) 28p6 , 28-lead, 0.600" wide, plastic dual inline package (pdip) dimensions in inches and (millimeters) jedec standard ms-011 ab 28s , 28-lead, 0.300" wide, plastic gull wing small outline (soic) dimensions in inches and (millimeters) 28t , 28-lead, plastic thin small outline package (tsop) dimensions in millimeters and (inches)* 28u , 28-pin, ceramic pin grid array (pga) dimensions in inches and (millimeters)
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